Dynamo-electric machine



Sept. 28 1926.

G. H LELAND DYNAMO ELECTRIC MACHINE Original Filed Nov. 22, 1920 ATTORNEY Patented Sept. 28, 1926.

UNITED STATES PATENT OFFICE.

GEORGE E. LELAND, 0F DAYTON,

OHIQ, ASSIGNOR OF ONE-HALF TO THE LELAND ELECTRIC comram'. or DAYTON, ozno, A conrona'rrouor c1110.

DYNAMO-ELECTRIG MACHINE.

Original application filed November 22'. 1920, Serial No. 425,832. Divided and this application filed November 26, 1921.

This invention relates to improvements: in dynamo electric machmes-havrng particular reference to single-phase alternating current motors of the repulsion-starting and induc tion-running type, and is a division of the subject matter originally filed in my copending application for Letters Patent Serial No. 425,832, filed November 22, 1920.

In single-phase, alternating current motore, the straight repulsion type without compensating windings produces, as is well known, the most satisfactory starting characteristics, while the induction type with completely short-circuited armature, or rotor windings, produces the best operating characteristics aside from starting. These known conditions have led to the development of the now well known type of repulsion-induction motor in which the armature currents are secondary and which, while the a motor is in starting speed, flow through the commutated short-circuit and, as the motor approaches operating speed, the armature coils are automatically short-circuited in parallel and the secondary currents are no longer commutated.

In short-circuiting devices heretofore used in motors of this type, it has been the practice to use a centrifugal element mounted relative to the armature shaft and having its force generated by the speed of the motor to actuate the short-circuiting mechanism. Various movements, both rotary and axial and a combination of both, have been employed to effect contact of the short-circuiting element with the commutator to establish and disrupt the short circuit of the armature.

The object of the present invention is to provide lmproved short-circuiting mechanism for motors of the type above referred to, whereby simplicity of construction and the highest effectiveness of operation, both in starting and running, are obtained.

In the present invention I have also used a centrifugal element mounted relative to the armature shaft to control the short-cir-.

cuiting element, but- I employ an outwardly directed radial movement of both element-s to establish the short circuit, and an inwardly directed radial movement to disrupt the same, as distinguished from devices of earlier construction above referred to.

The construction of the present invention requires less parts and is simpler and more Serial No. 518,012.

keep the contact surfaces clean and, therefore, to form more effective contact relations therebetwe-en. Furthermore, the wiping action of the contact surfaces minimizes the tendency to create a spark when contact is made or broken. While I do not claim broad novelty relative to wiping contacts generally, the construction here shown is nevertheless of an improved and highly effective character.

Other objects and advantages realized in my invention will be apparent from the ac companying drawings and the herein detailed description thereof.

In the drawings:

Fig. 1 is an end elevation of the commutator of a repulsion-induction motor having my improved shortcircuiting mechanism applied thereto, a portion of the mechanism being broken away to better illustrate the relation of the parts;

Fig. 2 is a detail sectional view showing parts of the motor in relative relations, the parts being shown in idleor normal inoperative relation;

Fig. 3 is an. enlarged double detail sectional view showing parts in relative relations at different steps of the short-circuiting operation, and

the rection of forces exerted on the shortcircuiting element under low speed.

Fig. 5 is a diagrammatic view illustrating the direction of forces exerted on the shortcircuiting element under high speed.

The details of motor construction, here shown to illustrate my invention, consist of the armature shaft --l, rotor 2, commutator ring 3, and commutator segments or bars 4. These parts, being common'to electric motors, may be of any suitable construction.

The short-circuiting mechanism consists as herein shown of a series of segmental weights 5, arranged circumferentially relative to the armature shaft and operable outwardly therefrom by centrifugal F 4 is adiagrammatic view illustrating normal relation, as illustrated in Figs. 1 and 2 and restrained in their outward movement by a circumferentially arranged spring 6 which is adapted to be expanded by outward movement of the weights into contact with the commutator to establish the short-circuit and to be retracted by its own tension to disrupt the short-circuit.

In their normal inoperative relation adjacent weights 5 have their lateral edges contacting one with another and their inner edges contacting with the hub or sleeve 7 of a retaining plate 8. The outer edges of the weights are beveled or inclined toward the commutator as best shown in Fig. 3, thus spring 6 is disposed within the angle formed between the inclined ends of the weights and the outer face of the coinmutator ring 3, the spring. being in pressure contact with the two surfaces. As the weights are moved outwardly by the centrifugal force exerted thereon, the spring is moved into wiping engagement with the commutator se ments 4 and into contact with an inwardly inclined flange --9 of retaining plate 8, as shown in the illustration to the right in Fig. 3, thus pressure will be exerted on the spring in the direction indicated by the arrow D, the contact pressure of the spring with the commutator segments will be increased as final contact is made and a more positive contact relation effected, the direction of forces operating on the spring in effecting the short-circuiting contact being illustrated diagrammatically in Figs. 4 and 5, Fig. 4: illustrating the action under low speed and Fig. 5 under high speed. In these views A represents the direction of the centrifugal action on weights -5, 'B the contractile tension of spring 6, -C the direction of pressure of spring 6 on the commutator, and D the direction of pressure on the springby flange 9 of plate -8.

Operation of the motor, having particular reference to the short-circuiting mechanism, briefly stated, is as follows:

When the motor is at rest the weight elements are in normal position. In starting the motor operates by repulsion, the weights being moved outwardly by centrifugal force generated as the motor attains speed until contact is made between springs 6 and the commutator, when short-circuiting of the armature is effected and the motor changes automatically to operation by induction.

When the motor falls below operating speed.

the centrifugal force abates accordingly, and the weights under restraint of spring 6 are retracted, thus breaking the contact between the spring and the commutator and disrupting the short-circuit when the motor again changes automatically to operation by repulsion.

I regard my invention broadly as a radical departure in principle and construction from short-circuiting devices of this character heretofore made, having particular reference to the spring-restrained, radially movable weight elements whereby contact with the commutator is made and broken to effect and disrupt short-circuiting of the armature, and the inclined edges of the weights which in their relation with the spring act to exert angular pressure through the spring on the commutator with increasin pressure as final contact is made to establish the short-circuit, thus acting to increase the effectiveness of the wiping action of the contact surfaces and of the short-circuit thereby established. The principle of the invention, as broadly and specifically applied in these particulars, is defined in the appended claims.

Having described my invention, I claim:

1. A short-circuiting device for electric motors, including in combination with a commutator, radially movable segmental weights, a circumferentially arranged tension member in engagement with all of said segmental weights, such member tending to restrain centrifugal movement of said weights and adapted to engage said commutator when said weights are moved under centrifugal action.

2. In short-circuiting mechanism for electric motors, including in combination with a commutator, a series of weight elements arranged circumferentially and operable radially relative to the motor shaft, and an electrically conductive tension element arranged circumferentially of the weight elements and operable radially therewith through centrifugal action of the weights into wiping engagement with said commutator.

3. In short-circuiting mechanism for electric motors, includin in combination with a commutator, a series of weight elements arranged circumferentially and operable radially relative to the motor shaft and having inclined outer peripheral edges, and an electrically conductive tension member arranged. circumferentially in cooperative relation with said inclined edges and movable outwardly with the weights through centrifugal action thereof and with increasing pressure into wiping engagement with the commutator.

4. In short-circuiting mechanism for elec tric motors, including in combination with a commutator, a retaining member on the motor shaft, spaced from the commutator and inclined relative thereto, a series of segmental weight elements operable radially between the commutator and said retaining member and having their outer ends inclined toward the commutator, an electrically conductive tension element arranged circumferentially of said weight elements in cooperative relation with the inclined ends thereof and said inclined retaining member and movable outwardly with the weights into engagement 'with the commutator.

5. In short-circuiting mechanism for electric motors, including in combination .with

arranged circumferentially of said weights in cooperative relation, with their said beveled edges andmovable outwardly with a the weights through centrifugal action thereof into wiping eontactwith the commutator. 43,

6. In short-circuit'ing mechanism for electric motors, including 'incol'nbination with a commutator, anretainingrnpmber on the motor shaft spaced from, the commutator and having its outer edgelinclined toward the commutatorya series of segmental weights operable radially between the commutator and said retaining member and; having their outer ends inclined toward the commutator, and an electrically conductive tension element arranged circumferentially in cooperative relation with the inclined ends of all of said weights and the inclined portion of said retaining member and movable with theweights through centrifugal action thereof with increasing pressure on the tension element in a plurality of planes as said tension element is moved into wiping contact with the commutator.

I. In short-circuiting mechanism for elec- 'tric motors, including in combination with a commutator, a retainingmember on the motor shaft spaced from the commutator and inclined inwardly relative thereto, a series of segmental weights operable between the commutator and said retaining mmber, and an electrically conductive tension element disposed between the weights and the inclined portion of said retaining member and adapted to be moved through centrifugal action of said weights into wiping contact relation with the commutator.

8. In short-circuiting mechanism for electric motors, including in combination with a commutator, a retaining member on the motor shaft spaced from the commutator and inclined inwardly relative thereto, a series of segmental weights operable between the commutator and said retaining member, and an electrically conductive tension element disposed between said weights and the inclined portion of said retaining member and movable with the weights through centrlfu al action thereof into engagement with tie commutator and out of engagement with the commutator through normal tension contraction.

9. In an alternating current motor, an armature shaft, a commutator mounted thereon, an annular member also mounted on said shaft opposite the commutator, a series of centrifugal elements, free to move outwardly, mounted between the annular member and commutator, and a flexible element adapted to be moved outwardly by the centrifugal elements, when the armature shaft attains a certain speed, to make contact between the annular member and the commutator for the purpose of short-circuiting the latter.

10.'In a short-circuiting mechanism for single-phase, alternating current motors and in combination with the armature and commutator thereof, cooperating weight and spring elements operable radially relative to the armature shaft, the spring element being electrically conductive and adapted to be moved slidably-into wiping contact with the commutator to eflect short-circuiting of the armature, whereby said contact is made with increasing pressure as the weights move outwardly.

d 11. In short-circuiting mechanism for single-phase, alternating current motors and in combination with the armature and commutator thereof, a plurality of weight elementsarranged circumfe rentially and operable radially relative to the armature shaft, :1 spring element arranged circumferentially of the weight elements and movable radially therewith, means to obstruct the movement of said spring whereby to cause'the spring pressure to be exerted on the weight elemerits radially and in a plane angular to the plane of said radial mor ement, one of said elements being electrically conductive and adapted to'be moved into contact with the commutator to short-circuit the armature whereby said contact is made with increasing pressure as the weights move outwardly. 12. In a motor including in combination with an armature shaft, a commutator and an annular member spaced one from the other on said shaft and inclined one toward the other to restrict the space therebetween outwardly, a series of segmental weights ar ranged circumferentially of said shaft and free to move centrifugally outwardly in the space between said annular members, each of said weights having its outer edge formed at an angle whereby the weights collectively present conically arranged surfaces, a flexible element arranged circumferentially of said conical surface and coacting therewith to restrain the centrifugal-movement of said weights and to exert lateral pressure thereom increasingly as the flexible element enters said restricted space to effect shortcircuiting of the the motor.

- 13- 111 an alterna g c r en m t an armature shaft, :1 commutator thereon, an annular member also mounted -on said shaft opposite the eommutator,the annular member and the commutator being inclined one toward the other whereby to restrict the space therebetween outwardly, a series of centrifugal elements, free to 'move outwardly betweenthe annular member and the commutator, and a flexible element trifugal elements into said restricted space,

when the armature shaft attains a certain speed, to make contact between the annular member and the commutator for the purpose of short-cireuiting the motor.

In testimony whereof, I aifix my signature.

GEORGE H. LELAND. 

